net-next: mediatek: bring up QDMA RX ring 0

This patch is in preparation for adding HW flow and QoS offloading. For
those features to work, the driver needs to bring up the first QDMA RX
ring. This ring is used by the PPE offloading HW.

Signed-off-by: John Crisp in <john@phrozen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>